THE NEPHRIDIA OF THE POLYOH^TA. 721 



In Glycera the genital funnel is developed even in young 

 and immature specimens, and is not known to open to the 

 exterior at any time. It is situated in front of the septum^ 

 provided with one long lip extending on to the body-wall in 

 some species, and with another lip leading into a sac. This 

 pouch of the coelomic epithelium, which I have called the 

 nephridial sac, varies greatly in size in diiferen.t species. 

 Into it are driven floating cells from the coelovn by the action 

 of the cilia of the genital funnel. Tnus waste material is 

 accumulated in the nephridial f^-^c, brought there by amoebo- 

 cytes and by the red corpascles or hsematocytes, which may 

 also be both amoeboid and phagocytal. 



The nephridial sac is but little developed in Glycera 

 convolutus, much larger in Gr. unicornis, and best de- 

 veloped in G. siphono stoma. In the two latter species it 

 is provided with a cascal outgrowth, incompletely subdivided 

 into secondary chambers. Special granular cells are found 

 loose in the secondary chambers and main sac. The caecum 

 lies along the nephridial canal, and probably represents that 

 region of the funnel which in other forms is known to open 

 into the nephridium. 



The nephridium itself is closely connected with the ne- 

 phridial sac. It is blind internally, and opens externally by a 

 pore on the ventral surface. The canal passes inwards and 

 forwards through the next septum to the genital funnel, and 

 then spreads over the nephridial sac, covering it more or less 

 completely. The lumen of the nephridium in this region 

 branches repeatedly, a spongework being formed by the 

 numerous primary and secondary canals. The latter dilate 

 at intervals into chambers, on the outer ccelomic surface of 

 which are situated the solenocytes. These cells are thus 

 scattered over the inner extremity of the nephridium, which 

 itself spreads over the sac. In Glycera convolutus and 

 G. siphonostoma the solenocytes are arranged in small 

 groups of two, three, or more, the cell-bodies containing the 

 nuclei being supported at the free extremities of the tubes, 

 and resting against each other; but in G. unicornis they 



